Multimedia server with channel control module and methods for use therewith

ABSTRACT

A multimedia server module includes a first transceiver module that modulates an encoded signal to produce a first radio frequency (RF) signal and that transmits the first RF signal to a client module over a first transceiver channel when the first transceiver module is in a transceive mode. The first transceiver module includes a first channel control module that performs a first channel scan when the first transceiver module is in a scan mode, that determines at least one performance parameter of the first transceiver channel and asserts a low performance signal when the at least one performance parameter compares unfavorably to a performance threshold, and that switches the first transceiver module to a selected alternative transceiver channel when the low performance signal is asserted.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to wireless communication systems andmore particularly to in-home local area networking for content such asmultimedia.

BACKGROUND OF THE INVENTION

With the number of households having multiple television setsincreasing, and many users wanting the latest and greatest video viewingservices. As such, many households have multiple satellite receivers,cable set-top boxes, modems, et cetera. For in-home Internet access,each computer or Internet device has its own Internet connection. Assuch, each computer or Internet device includes a modem.

As an alternative, an in-home wireless local area network may be used toprovide Internet access and to communicate multimedia information tomultiple devices within the home. In such an in-home local area network,each computer or Internet device includes a network card to access aserver. The server provides the coupling to the Internet. The in-homewireless local area network can also be used to facilitate an in-homecomputer network that couples a plurality of computers with one or moreprinters, facsimile machines, as well as to multimedia content from adigital video recorder, set-top box, broadband video system, etc.

In such wireless communication systems, the data is transmitted viaradio frequencies (RF) in accordance with one or more data transmissionprotocols. In any type of wireless communication system, the receptionof transmitted information can be susceptible to fading, interferenceand noise over the communication channel that degrades the quality ofthe received information, decreases the transmission rate or otherwiselowers the performance of the communication channel. Therefore, a needexists for a method and apparatus for a communication system to overcomethe above-mentioned issues in a manner that can efficiently implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a pictorial representation of a multimedia client serversystem in accordance with an embodiment of the present invention.

FIG. 2 presents a pictorial representation of a multimedia client/serversystem in accordance with an embodiment of the present invention.

FIG. 3 presents a block diagram representation of a multimediaclient/server system in accordance with an embodiment of the presentinvention.

FIG. 4 presents a block diagram representation of a multimedia servermodule 12 in accordance with an embodiment of the present invention.

FIG. 5 presents a block diagram representation of a client module 200 inaccordance with an embodiment of the present invention.

FIG. 6 presents a block diagram representation of a multimediaclient/server system in accordance with an embodiment of the presentinvention.

FIG. 7 presents a block diagram representation of a multimedia servermodule 12′ in accordance with an embodiment of the present invention.

FIG. 8 presents a block diagram representation of a client module 200 inaccordance with an embodiment of the present invention.

FIG. 9 presents a schematic block diagram representation of atransceiver module 290 in accordance with an embodiment of the presentinvention.

FIG. 10 presents a schematic block diagram representation of atransceiver module 310 in accordance with an embodiment of the presentinvention.

FIG. 11 presents a graphical representation of a frequency spectrum inaccordance with an embodiment of the present invention.

FIG. 12 presents a graphical representation of a frequency spectrum inaccordance with an embodiment of the present invention.

FIG. 13 presents a flow chart representation of a method in accordancewith an embodiment of the present invention.

FIG. 14 presents a flow chart representation of a method in accordancewith an embodiment of the present invention.

FIG. 15 presents a flow chart representation of a method in accordancewith an embodiment of the present invention.

DETAILED DISCUSSION OF A PREFERRED EMBODIMENT

FIG. 1 presents a pictorial representation of a multimedia client serversystem in accordance with an embodiment of the present invention. Themultimedia client server system includes multimedia server 12, clientmodules 34, 36, 38, 40 and 42 that are coupled to clients 26, 28, 30,32, and 34, and a plurality of multimedia sources. The multimediasources include video cassette recorder (VCR) 86, digital video disk(DVD) player 82, digital video recorder (DVR) 102, digital audio storagedevice 104, DVD audio 106, radio receiver 108, CD player 110, publicswitch telephone network 66, wide area network 44 (such as a privatenetwork, public network, satellite network, cable network and/or theInternet) for accessing broadcast, stored or streaming audio, videoand/or other multimedia content and/or any other type of audio, videoand/or multimedia source 24.

In an embodiment of the present invention, the clients 26-34 may selectplayback from, and/or connection to, any one of the multimedia sources.The selection request from each client module would identify the desiredmultimedia source, the client, the desired service and any otherinformation to assist the multimedia server 12 in processing therequest. As such, one client may be accessing the Internet, whileanother client is watching a satellite broadcast channel, while anotheris listening to a CD playback, while another is talking on thetelephone, and yet another is watching a DVD playback. This is all donevia the multimedia server 12 without requiring the clients to havedirect access to the multimedia sources and without the requirement thateach client have its own multimedia source and/or multimedia sourceconnection.

The multimedia server 12 and one or more of the client modules 34, 36,38, 40 and 42 include one or more features for increasing thereliability and quality of wireless transmission in accordance with thepresent invention, as will be described in greater detail in the Figuresthat follow, and in particular, with reference to FIGS. 2-15.

FIG. 2 presents a pictorial representation of a multimedia client/serversystem in accordance with an embodiment of the present invention. Inparticular, a multimedia client/server system includes a multimediaserver 12, a plurality of client modules 34, 36, 38, 40 and 42 that areoperably coupled to a plurality of clients 25, 26, 28, 30, and 32. Themultimedia server 12 is operably coupled to receive a plurality ofchannels 46 from a multimedia source 23. The multimedia source 23 can bea broadcast, stored or steaming multimedia signal, from a video cassetterecorder (VCR) 86, digital video disk (DVD) player 82, digital videorecorder (DVR) 102 digital audio storage device 104, DVD audio 106,radio receiver 108, CD player 110, public switch telephone network 66,wide area network 44 (such as a private network, public network,satellite network, cable network and/or the Internet for accessingbroadcast, stored or streaming audio, video and/or other multimediacontent) and/or any other type of audio, video and/or multimedia source24. As one of average skill in the art will appreciate, the multimediaserver 12 may be a stand-alone device, may be incorporated in asatellite receiver, set-top box, cable box, HDTV tuner, homeentertainment receiver, et cetera. In addition, the multimedia server 12may be implemented using discrete components, integrated circuits,and/or a combination thereof.

The multimedia server 12 communicates with the plurality of clientmodules 34, 36, 38, 40, and 42 via a radio frequency communication path.As such, the multimedia server 12 and each of the client modules 34, 36,38, 40 and 42 each include a transceiver that operates to send andreceive data via the communication path.

As shown, each client module is operably coupled to one of the clients.For example, client module 34 is operably coupled to client 26, which isrepresentative of a personal digital assistant. Client module 36 isoperably coupled to client 28, which is representative of a personalcomputer. Client module 38 is operably coupled to client 30, which isrepresentative of a monitor (e.g., LCD monitor, flat panel monitor, CRTmonitor, et cetera). Such a monitor may include speakers, or a speakerconnection, control functions including channel select, volume control,picture quality, et cetera. Client module 40 is operably coupled toclient 32, which may be a television set, high definition television(HDTV), standard definition television (SDTV), a home theatre system, etcetera. Client module 42 is operably coupled to client 25, which isrepresentative of a laptop computer.

As one of average skill in the art will appreciate, each client modulemay be a separate device from its associated client or embedded withinthe client. In addition, one of average skill in the art will furtherappreciate that the client modules 34, 36, 38, 40 and 42 may beimplemented utilizing discrete components and/or integrated circuits.

In an embodiment of the present invention, each of the clients, via itsassociated client module, selects one or more channels from theplurality of channels 46. As shown, client 26 has selected channel 3 ofthe plurality of channels for viewing. Accordingly, client module 34relays the channel selection of channel 3 to the multimedia server 12.The multimedia server 12 selects channel 3 from the plurality ofchannels 46. The data corresponding to channel 3 is then timemultiplexed with the data for the other channels and transmitted fromthe multimedia server 12 to each of the client modules 34, 36, 38, 40and 42. Client module 34 monitors the transmission from the multimediaserver 12 and extracts the data corresponding to channel 3. Theextracted data for channel 3 is then provided to the client 26 fordisplay.

Client module 36, 38, 40 and 42 perform a similar function for theirassociated clients 28, 30, 32 and 25, respectively. As shown, client 28has selected channel 505, client 30 has selected channel 106, client 32has selected channel 206 and client 25 has selected channel 9. Theclient modules 36, 38, 40 and 42 provide the channel selection of itsrespective client to the multimedia server 12. Multimedia server 12extracts the selected channels from the plurality of channels for eachselection request, multiplexes the data for each of the selectedchannels (for this example channel 3, 9, 106, 206 and 505) into a streamof data. The stream of data is then transmitted to each of the clientmodules. Each client module extracts the appropriate data of theselected channel for its respective client. For example, client module36 monitors the transmitted data for data related to channel 505, clientmodule 38 monitors for data related to channel 106, client module 40monitors the transmission for data related to channel 206 and clientmodule 42 monitors the transmission for data related to channel 9.

From each client's prospective, the client 25, 26, 28, 30 and 32 hasindependent access to the multimedia source 23. Accordingly, client 26may at any time change its channel selection from, for example, channel3 to channel 120. The client module 34 provides the channel selectionrequest which may be the absence of acknowledgements to the multimediaserver 12, which now retrieves data related to channel 120 for client 36as opposed to channel 3. As an alternate embodiment, the functionalityof client modules 34, 36, 38, 40 and 42 may vary. For example, clientmodule 34 may not provide all the independent functionality that clientmodule 36 does. For example, client module 34 may not have independentchannel selection capabilities but only selecting channels that one ofthe other clients have selected. Alternatively, one client module mayservice a plurality of clients.

FIG. 3 presents a block diagram representation of a multimediaclient/server system in accordance with an embodiment of the presentinvention. In particular, the multimedia client/server system includesmultimedia server 12 that transmits a multimedia signal 214, such as abroadcast, stored or streaming signal from multimedia source 23.Multimedia server module 12 transmits, via antennas 206, an radiofrequency (RF) signal that contain the multimedia content frommultimedia signal 214. This RF signal is transmitted at a carrierfrequencies corresponding to a channel such as channel A or channel B ofan RF spectrum. Client module 200, (such as client modules 34, 36, 38,40 and 42) receives the RF signal via antennas 210 and produces adecoded output signal 216.

It should be noted that channel A and channel B represent differentchannels of an RF spectrum corresponding to different carrierfrequencies. This is as opposed to channels 3, 9, 106, 206 and 505discussed in association with FIG. 2 where “channel”, is this context,was used primarily to denote difference streams of multimedia contentsuch as “The Weather Channel”, “The Discovery Channel” or “Gone with theWind”. In the event that noise, interference or fading hamper theperformance of one of the channels, the multimedia server module 12 canswitch to a different channel. Further functions and features of themultimedia server module 12 and client module 200 are presented inconjunction with FIGS. 4-15 that follow.

FIG. 4 presents a block diagram representation of a multimedia servermodule in accordance with an embodiment of the present invention. Inparticular, multimedia server module 12 includes an encoder module 230for producing an encoded signal 232 from unencoded multimedia inputsignal 214. In an embodiment of the present invention, the encodingscheme may be one or more of multilevel, multiphase and multifrequencyencoding, non-return to zero encoding, Manchester encoding, blockencoding and/or nB/mB encoding wherein n>m. For example, the nB/mB maybe 4B/5B encoding where 4 bits of actual data are converted into 5 bitsof encoded data.

Encoding may further include compression, transrate and transcodeencoding of the multimedia signal based on the content and format ofmultimedia signal 214 and the bandwidth and performance of channels Aand/or channel B. In an embodiment, the multimedia signal 214 includesan analog composite video signals that is formatted in any of a numberof video formats including National Television Systems Committee (NTSC),Phase Alternating Line (PAL) or Sequentiel Couleur Avec Memoire (SECAM).The encoded signal 232 may be digitized, compressed, and channel codedfor transmission at low data rates in weak channel conditions or higherdata rates in stronger channel conditions. Alternatively, multimediasignal 214 can be already in a digital format such as a Motion PictureExperts Group (MPEG) format (such as MPEG1, MPEG2 or MPEG4), Quicktimeformat, Real Media format, Windows Media Video (WMV) or Audio VideoInterleave (AVI), or another digital video format, either standard orproprietary. In this case, the encoding performed by encoder module 230may be limited to encoding of the data for the channel, based on thestrength or quality of the channel conditions, with or without furthercompression.

Multimedia server module 12 further includes transceiver module 234 formodulating the encoded signal 232 to produce a RF signal 236 thatincludes multimedia content such as a packetized video signal at a firstcarrier frequency and for transmitting the RF signal 236 over channel Ausing antenna 206. In addition, transceiver modules 234 produces backchannel output 310 based on an RF signal received from the client module200 over channel A.

In an embodiment of the present invention, transceiver module 234 isselectively tunable to a plurality of other carrier frequencies inresponse to channel selection signals 220 and 222. For instance, in animplementation of the multimedia server module 12 and client module 200using wireless transmission link in the United States that conforms withthe IEEE 802.11g standard, channels A and B can be selected as any ofthe 11 allocated channels. In an embodiment of the present invention,the channel selection signals can be preprogrammed into multimediaserver module 12, dynamically chosen based on a site survey that scansthe available channels to determine two suitable channels for use,received from the client module 200 or arbitrated between the clientmodule 200 and multimedia server module 12, or selected under usercontrol. Similarly, channels A and B can be implemented as channels of abroadband wireless access network that conforms to at least one of thefollowing standards: 802.11a, b, n or other 802.11 standard, UltraWideband (UWB), or Worldwide Interoperability for Microwave Access(WiMAX).

Transceiver module 234 includes a channel control module 330 is operableto scan alternative channels, and selected a particular alternativechannel, such as channel B, in the event that the performance of channelA degrades. In an embodiment of the present invention, channel controlmodule 330 enters into a scan mode, such as in response to thedegradation of the performance of channel A, at a time that transceiver234 would otherwise be inactive such as during a quiet time betweenvideo packet acknowledgements, or periodically (such as once per second,once per minute or other period), after a corresponding time intervalhas expired. In scan mode, channel control module performs a channelscan that determines at least one performance parameter of the channeland asserts a low performance signal when the at least one performanceparameter compares unfavorably to a performance threshold. In response,channel control module 330 switches the first transceiver module 236 toa selected alternative transceiver channel, such as channel B, when thelow performance signal is asserted.

In an embodiment of the present invention, the channel scan includesdetermining at least one performance parameter of an alternativetransceiver channel, such as a bit error rate, signal to noise ratio,received signal strength indication, noise measurement, interferencemeasurement, channel gain or other channel performance parameter. Thechannel control module 330 is further operable to switch the transceivermodule 234 to the transceive mode to transmit the RF signal 236 to theclient module 200 over the alternative transceiver channel when the atleast one performance parameter of the alternative transceiver channelcompares favorably to a performance threshold. In this fashion, thetransceiver module 234 perform only an abbreviated channel scan thatterminates when an acceptable channel is found. Alternatively, a morecomplete channel scan can be performed by determining a plurality ofperformance parameters for a plurality of alternative first transceiverchannels. An alternative transceiver channel can be determined bydetermining the channel with the “best” or most favorablecharacteristics based on one or more performance criteria.

When an alternative transceiver channel is identified, switch data isgenerated by the channel control module and transmitted to the clientmodule 200 and/or other client modules that are in communication withthe multimedia server module 12 to request a change of channel from theoriginal channel frequency to the frequency of the alternativetransceiver channel. In an embodiment of the present invention,multimedia server module 12 receives a client module list of acceptablechannels/channel frequencies from one or more client modules andcompares with its own locally generated multimedia server module list todetermine if a common acceptable channel/channel frequency can be found.In an embodiment, the channel control module 330 is further operable toarbitrate the switch to the alternative transceiver channel with theclient module. If one or more client modules in communication withmultimedia server module 12 disagrees with the change of channels,arbitration mechanisms such as voting or other mechanisms can beemployed to determine an acceptable alternative transceiver channel.

FIG. 5 presents a block diagram representation of a client module 200 inaccordance with an embodiment of the present invention. In particular,client module 200 includes transceiver module 244 for receiving RFsignal 246 over channel A or an alternate channel such as channel Bselected by multimedia server module 12 and for converting the RF signal246 into a baseband signal 248. In addition, transceiver module 244 isoperable to modulate back channel input 272 to produce RF signals sentto multimedia server module 12 over channels A and/or B.

In an embodiment of the present invention, multimedia server module 12and client module 200 use a wireless transmission link that conformswith the IEEE 802.11g standard that uses a 52-subcarrier orthogonalfrequency division multiplexing (OFDM) with a maximum data rate of 54Mbits/sec. The data rate is reduced in increments in response to adversechannel conditions from 48 mbits/sec, down to as low as 6 Mbits/sec bymodifying the modulation and effective coding rate from 64-quadratureamplitude modulation (64-QAM) to binary phase shift keying (BPSK). The52 subcarriers of a channel are spaced 312.5 kHz apart, where 48 of thesubcarriers carry data, and 4 subcarriers carry pilot tones. Basebandsignal 248 may be low intermediate frequency (IF) signals.

In an embodiment of the present invention baseband signal 248 canoptionally be formatted in a data format such as Universal Serial Bus(USB), Personal Computer Interface (PCI), Firewire, or small computerservice interface (SCSI), prior to decoding by decoder module 254however, other data formats, either standard or proprietary may likewisebe implemented within the broad scope of the present invention.

Client module 200 further includes decoder module 254 for decoding theoutput signal 252 into a decoded output signal, such as in a format usedby the attached client. In particular, further decoding of the data caninclude decompression of a compressed digital signal, formatting of avideo signal as in NTSC, PAL, SECAM, etc., and other formatting to matchthe input format of the client device.

In an embodiment of the present invention, transceiver module 244 isselectively tunable to a plurality of other carrier frequencies inresponse to channel selection signals 224. For instance, in animplementation of the multimedia server module 12 and client module 200using wireless transmission link in the United States that conforms withthe IEEE 802.11g standard, channels A and B can be selected as any twoof the 11 allocated channels. In an embodiment of the present invention,the channel selection signals can be preprogrammed into client module200, dynamically chosen based on a site survey that scans the availablechannels to determine two suitable channels for use, received from themultimedia server module 12 or arbitrated between the client module 200and multimedia server module 12, or selected under user control.

In an embodiment of the present invention, transceiver module 244includes a channel control module 330′ that is operable to scanalternative channels, and select one or more alternative channels, suchas channel B, in the event that the performance of channel A degrades.In another embodiment of the present invention, channel control module330′ enters into a scan mode at a time that transceiver 244 wouldotherwise be inactive such as during a quiet time between video packetacknowledgements, or periodically (such as once per second, once perminute or other period), after a corresponding time interval hasexpired. In scan mode, channel control module 300′ performs a channelscan that determines at least one performance parameter of the channeland asserts a low performance signal when the at least one performanceparameter compares unfavorably to a performance threshold. In response,channel control module 330′ provides this feedback to the multimediaserver module 12 and switches the transceiver module 244 to a selectedalternative transceiver channel, such as channel B, when commanded bymultimedia server module 12.

In an embodiment of the present invention, the channel scan includesdetermining at least one performance parameter of an alternativetransceiver channel, such as a bit error rate, signal to noise ratio,received signal strength indication, noise measurement, interferencemeasurement, channel gain or other channel performance parameter. Likechannel control module 330, channel control module 330′ is capable ofperforming either a complete or abbreviated scan.

When an alternative transceiver channel is identified, data is generatedby the channel control module 330′ and transmitted to the multimediaserver module 12 to request a change of channel from the originalchannel frequency to the frequency of the alternative transceiverchannel. In an embodiment of the present invention, multimedia servermodule 12 receives a client module list of acceptable channels/channelfrequencies from one or more client modules, such as client module 200and compares with its own locally generated multimedia server modulelist to determine if a common acceptable channel/channel frequency canbe found. In an embodiment, the channel control module 330′ is furtheroperable to arbitrate the switch to the alternative transceiver channelwith the multimedia server module 12. If one or more other clientmodules in communication with multimedia server module 12 disagrees withthe change of channels, arbitration mechanisms such as voting or othermechanisms can be employed to determine an acceptable alternativetransceiver channel.

FIG. 6 presents a block diagram representation of a multimediaclient/server system in accordance with an embodiment of the presentinvention. In particular, the multimedia client/server system includesmultimedia server 12′ that transmits via antennas 206 and 208, two radiofrequency (RF) signals that contain duplicate copies of the multimediacontent from multimedia signal 214. These two RF signals are transmittedat two carrier frequencies corresponding to either the same or differentchannels such as channel A and/or channel B of an RF spectrum. Clientmodule 200′, (such as client modules 34, 36, 38, 40 and 42) receivesthese two RF signals via antennas 210 and 212 and produces a decodedoutput signal 216.

Further functions and features of the multimedia server module 12 andclient module 200 are presented in conjunction with FIGS. 7 and 8.

FIG. 7 presents a block diagram representation of a multimedia servermodule in accordance with an embodiment of the present invention. Inparticular, multimedia server module 12′ many common elements ofmultimedia server module 12 that are referred to by common referencenumerals. In addition to transceiver module 234, multimedia servermodule 12′ includes transceiver module 235 that modulates the encodedsignal 232 to produce RF signal 237 at a second carrier frequency andtransmits the RF signal 237 over either channel A or channel B usingantenna 208 when transceiver module 235 is in transceive mode. Inaddition, transceiver module 235 produces back channel outputs 312 basedon RF signals received from the client module 200 over channels A and/orB. In an embodiment of the present invention, the back channel outputscan be recombined in similar fashion to the recombination that will bedescribed in conjunction with client module 200′ for the forwardtransmission path in association with FIG. 8.

In an embodiment of the present invention, transceiver modules 234 and235 are selectively tunable to a plurality of other carrier frequenciesin response to channel selection signals 220 and 222. For instance, inan implementation of the multimedia server module 12 and client module200 using wireless transmission link in the United States that conformswith the IEEE 802.11g standard, channels A and B and other alternativetransceiver channels can be selected as any two of the 11 allocatedchannels. In an embodiment of the present invention, the channelselection signals can be preprogrammed into multimedia server module12′, dynamically chosen based on a site survey that scans the availablechannels to determine two suitable channels for use, received from theclient module 200′ or arbitrated between the client module 200′ andmultimedia server module 12′, or selected under user control.

In an embodiment of the present invention, antenna 206 is placed adistance apart from antenna 208 so as to be spatially diverse. In anembodiment of the present invention, the spacing is substantially ≧¼wavelength of the corresponding carrier frequency. However, otherspacings may likewise be implemented as will be apparent to one skilledin the art when presented the disclosure herein.

Like transceiver module 234, transceiver module 235 includes a channelcontrol module 330 is operable to scan alternative channels in scanmode, and select a particular alternative channel, such as channel B orsome other channel, in the event that the performance of channel Adegrades. In an embodiment of the present invention, channel controlmodule 330 enters into a scan mode, such as in response to thedegradation of the performance of channel A or B, at a time thattransceiver 234 would otherwise be inactive, such as during a quiet timebetween video packet acknowledgements, or in periodically (such as onceper second, once per minute or other period), after a corresponding timeinterval has expired. In scan mode, channel control module performs achannel scan that determines at least one performance parameter of thechannel and asserts a low performance signal when the at least oneperformance parameter compares unfavorably to a performance threshold.In response, channel control module 330 switches the first transceivermodule 236 to a selected alternative transceiver channel, such aschannel B, when the low performance signal is asserted.

In an embodiment of the present invention, the channel control module330 of transceiver modules 234 and 235 communicate with one another viatransceiver scan signals 314 and 315. In particular, channel scanresults including performance results for alternative channelsdetermined by one transceiver can be used to select a selectedalternative transceiver channel, not only for that transceiver, but alsofor the other transceiver. So, for instance, if the channel performanceof a first transceiver degrades, the transceiver scan signal 314 or 315can request the second transceiver to perform a channel scan and selecta selected alternative transceiver channel for the first transceiver, orfor both transceivers. In a further mode of operation, each transceivercan operate independently, performing independent channel scans andselecting channels and alternative channels that may be either the sameor different from the channel frequencies used by the other transceiver.

In an embodiment of the present invention, only one of the transceivermodules can be in the scan mode at any given time. In particular, whenthe performance of the channel used by a particular transceiver moduledecreases below a threshold, a time period expires or some othercondition is present, the transceiver module can enter a scan mode toscan the channel conditions of other available channels, either to findbetter channel conditions or perform a periodic channel survey. When thescan mode is entered, the full burden of sending and receiving data toand from the client module falls to the other transceiver module.

When transceiver modules 234 and 235 enter the scan mode, eachtransceiver module asserts a scan flag that is passed to the othertransceiver via either transceiver scan signal 314 or 316. Beforeentering the scan mode, each transceiver module first checks to see thatthe other transceiver is not currently in the scan mode by determiningif the scan flag of the other transceiver module is currently asserted.If the scan flag of the other transceiver module is deasserted, it issafe to enter into scan mode. If the scan flag of the other transceivermodule is asserted, the transceiver module must remain in the transceivemode to continue to send and receive data from any client modules in thesystem.

In a further embodiment of the present invention, wherein thetransceiver modules 234 and 235 perform channel scans during periods ofinactivity or quiet times, such as between video acknowledgements, bothtransceiver modules may simultaneously perform channel scans withoutadversely impacting the required transmission of multimedia content.

FIG. 8 presents a block diagram representation of a client module 200′in accordance with an embodiment of the present invention. Inparticular, client module 200′ includes may common elements of clientmodule 200 that are referred to by common reference numerals. Inaddition, client module 200′ includes transceiver module 245 thatreceives RF signal 247 from a multimedia server module 12′ and convertsRF signal 247 into a baseband signal 249. The benefits of spatial and/orfrequency diversity are realized by recombination module 250 thatcombines the baseband signal 248 and baseband signal 249 into outputsignal 252. Duplicate copies of the multimedia content are received,aligned and combined in such a fashion to compensate for data that ismissing or corrupted from one or the other of the received signals. Inaddition, transceiver modules 244 and 245 are operable to modulate backchannel input 272 to produce RF signals sent to multimedia server module12′ over channels A and/or B.

In an embodiment of the present invention, recombination module 250utilizes a maximum ratio recombination on a subcarrier basis for each ofthe 48 data-bearing subcarriers of the channel to combine the basebandsignals 248 and 249 into a single output signal 252. However, otherrecombination schemes may likewise be implemented including phasealignment of the baseband signals and summation, or choosing the signalwith the maximum received signal strength or with the highest signal tonoise ratio, etc. This recombination compensates for the many of theeffects of fading, interference (including multipath interference), andnoise. Baseband signals 248 and 249 may also be low intermediatefrequency (IF) signals.

In an embodiment of the present invention recombination module 250formats output signal 252 in a data format such as Universal Serial Bus(USB), Personal Computer Interface (PCI), Firewire, or small computerservice interface (SCSI), however, other data formats, either standardor proprietary may likewise be implemented within the broad scope of thepresent invention.

In an embodiment of the present invention, transceiver modules 244 and245 are selectively tunable to a plurality of carrier frequencies, thatmay be the same carrier frequency or different carrier frequenciescorresponding to channels A and/or B or to other alternative transceiverchannels in response to channel selection signals 224 and 226. Forinstance, in an implementation of the multimedia server module 12′ andclient module 200′ using wireless transmission link in the United Statesthat conforms with the IEEE 802.11g standard, channels A and B can beselected as any two of the 11 allocated channels. In an embodiment ofthe present invention, the channel selection signals can bepreprogrammed into client module 200′, dynamically chosen based on asite survey that scans the available channels to determine two suitablechannels for use, received from the multimedia server module 12′ orarbitrated between the client module 200′ and multimedia server module12′, or selected under user control.

In an embodiment of the present invention, antenna 210 is placed adistance apart from antenna 212 so as to be is spatially diverse. In anembodiment of the present invention, the spacing is greater than orequal to substantially ¼ wavelength of the corresponding carrierfrequency. However, other spacings may be likewise be implemented aswill be apparent to one skilled in the art when presented the disclosureherein.

Both transceivers 244 and 245 can include a channel control module 330′that includes the functions as previously described. In an embodiment ofthe present invention, only one of the transceiver modules can be in thescan mode at any given time. In particular, when the performance of thechannel used by a particular transceiver module decreases below athreshold, a time period expires or some other condition is present, thetransceiver module can enter a scan mode to scan the channel conditionsof other available channels, either to find better channel conditions orperform a periodic channel survey. When the scan mode is entered, thefull burden of sending and receiving data to and from the client modulefalls to the other transceiver module.

When transceiver modules 244 and 245 enter the scan mode, eachtransceiver module asserts a scan flag that is passed to the othertransceiver via either transceiver scan signals shared between these twotransceiver modules. Before entering the scan mode, each transceivermodule first checks to see that the other transceiver is not currentlyin the scan mode by determining if the scan flag of the othertransceiver module is currently asserted. If the scan flag of the othertransceiver module is deasserted, it is safe to enter into scan mode. Ifthe scan flag of the other transceiver module is asserted, thetransceiver module must remain in the transceive mode to continue tosend and receive data from any client modules in the system.

In a further embodiment of the present invention, wherein thetransceiver modules 244 and 245 perform channel scans during periods ofinactivity or quiet times, such as between video acknowledgements, bothtransceiver modules may simultaneously perform channel scans withoutadversely impacting the required transmission of multimedia content.

FIG. 9 presents a schematic block diagram representation of atransceiver module in accordance with an embodiment of the presentinvention. While the communication between multimedia server module12/12′ and client module 200/200′ has been described primarily in termsof the forward transmission of multimedia content from the multimediaserver module 12/12′ to the client module 200/200′, in an embodiment ofthe present invention, a reciprocal back channel is also present thatallows for the flow of control and signaling data, channel selectionsand the selection of the content of multimedia signal 214 as well as theflow of other user data such as an Internet uplink, transmittedtelephony signals, etc. Transceiver module 290, such as transceivers 244and/or 245 (optionally implemented without a channel control module330′), includes a transmitter 292 for modulating a baseband (BB) input300 by a carrier frequency derived from channel selection signal 296,such as channel selection signals 220, 222, 224 and 226, to form an RFoutput 302. In addition, receiver 294 receives an RF input 304 that isdemodulated, based on a carrier frequency derived from channel selectionsignal 296. Baseband input 300 and baseband output 306 may also be lowIF signals.

In an embodiment of the present invention, antenna 298, such as antennas206, 208, 210 and 212, includes a dedicated antenna element fortransmitter 292 and receiver 294. In other embodiments however, a singleantenna element can be coupled so as to be shared by both transmit andreceive paths.

FIG. 10 presents a schematic block diagram representation of atransceiver module in accordance with an embodiment of the presentinvention. Transceiver module 310 is shown that includes many of theelements of transceiver module 290 presented in conjunction with FIG. 9,and that can be used to implement transceiver modules 234 and/or 235 ofFIGS. 4 and 7 and transceiver modules 244 and/or 245 of FIGS. 5 and 8(with the replacement of channel control module 330′ for channel controlmodule 330). Channel control module 330 (or 330′) performs the functionspreviously described. In particular, channel control module 330 (or330′) generates channel selection signal 296 to tune transmitter 292 andreceiver 294 to the original transceiver channel or to one or morealternative channels. While in the scan mode, scan module 330 (or 330′)monitors the input to transmitter 292 and the output of receiver 294 toassess the performance parameters of the alternative transceiverchannels and to control and arbitrate the switching of the channelfrequencies between multimedia server module 12 or 12′ and one or moreclient modules in communication therewith.

Further, channel control module 330 (or 330′) is operable to generatetransceiver scan signal 334 of transceiver module 310 (for examplecorresponding to transceiver scan signals 314 and 316 of transceivermodules 234 and 235 or transceiver scan signals of transceiver modules244 and 245). In addition, channel control module 330 (or 330′)optionally prevents transceiver module 310 from entering scan mode whentransceiver scan signal 336, corresponding to a companion transceivermodule, is asserted.

In an embodiment of the present invention, channel control module 330(or 330′) can be implemented using a single processing device or aplurality of processing devices. Such a processing device may be amicroprocessor, co-processors, a micro-controller, digital signalprocessor, microcomputer, central processing unit, field programmablegate array, programmable logic device, state machine, logic circuitry,analog circuitry, digital circuitry, and/or any device that manipulatessignals (analog and/or digital), optionally based on operationalinstructions that are stored in a memory that may be a single memorydevice or a plurality of memory devices. Such a memory device caninclude a hard disk drive or other disk drive, read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. Note that when the channel control moduleimplements one or more of its functions via a state machine, analogcircuitry, digital circuitry, and/or logic circuitry based onoperational instructions, the memory storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry.

While the present invention has been described primarily in terms of themultimedia server module 12/12′ including channel scan module 330,client modules 200/200′ can also implement transceiver modules 244 and245 with channel scan module 330 of transceiver module 310 that canoptionally controls the channel selection for itself and multimediaserver module 12/12′ by performing these aspects of the presentinvention previously attributed multimedia server module 12/12′.

FIGS. 11 and 12 present graphical representations of a frequencyspectrum in accordance with an embodiment of the present invention. Inan embodiment of the present invention, channel A and channel B areimplemented using any two channels of the available spectrum such as theInstitute of Electrical and Electronics Engineers (IEEE) 802.11xcompliant wireless link in either the 2.4 gigahertz (GHz) frequency bandor the 5 GHz frequency band. As used herein 802.11x refers to a systemconforming to any of the IEEE 802.11 family of specifications. In FIG.11, the channels 404 and 406 that are used, such as channel A andchannel B, have corresponding carrier frequencies that fall withinseparate frequency bands 400 and 402. In an embodiment of the presentinvention, the frequency band 400 corresponds to the 2.4 GHz frequencyband and the frequency band 402 corresponds to a 5 GHz frequency band.This diversity between frequency bands potentially increases thediversity between channels 404 and 406 and potentially increases thequality of the recombined output signal 252 when two differentfrequencies are used. Further, when channel A is the original frequencyof operation and channel B is a selected alternative frequency, itallows the transceiver to avoid interference that is present over anentire frequency band, such as the 2.4 GHz band in this example. In analternative embodiment of the present invention shown in FIG. 12,channel 406 and channel 408 are chosen from different portions of asingle frequency band such as, respectively, the upper half and lowerhalf of the frequency band 402. In general, the further the spacingbetween the carrier frequencies of channels A and B, the lesser thepossibility that a single source of interference could be present onboth channels.

The description above has been limited to spectrum reserved for 802.11xcompliant broadband access networks, in an alternative embodiment of thepresent invention, other spectrum and other wireless links includingUltra Wideband (UWB), Worldwide Interoperability for Microwave Access(WiMAX) and other wireless links can likewise be implemented.

FIG. 13 presents a flow chart representation of a method in accordancewith an embodiment of the present invention. In particular, a method ispresented for use in conjunction with one or more of the functions andfeatures described in association with FIGS. 1-12. In step 400, a firstchannel scan is performed when the first transceiver module is in a scanmode during a quiet time between video packet acknowledgements. In step402, at least one performance parameter of the first transceiver channelis determined wherein the first transceiver channel is a channel of abroadband wireless access network that conforms to at least one of thefollowing standards: 802.11x, Ultra Wideband (UWB), and WorldwideInteroperability for Microwave Access (WiMAX). In step 404, a lowperformance signal is asserted when the at least one performanceparameter compares unfavorably to a performance threshold. In step 406,the first transceiver module is switched to a selected alternativetransceiver channel when the low performance signal is asserted.

In an embodiment of the present invention, the first channel scanincludes determining at least one performance parameter of a pluralityof alternative transceiver channels and selecting the selectedalternative transceiver channel of the plurality of alternativetransceiver channels. Further, step 400 is optionally performed inresponse to the low performance signal and/or in response to theexpiration of a time interval.

FIG. 14 presents a flow chart representation of a method in accordancewith an embodiment of the present invention. In particular, a method ispresented for use in conjunction with one or more of the functions andfeatures described in association with the method of FIG. 13. In step510, switch data is transmitted to the client module.

FIG. 15 presents a flow chart representation of a method in accordancewith an embodiment of the present invention. In particular, a method ispresented for use in conjunction with one or more of the features andfunctions presented in association with the method of FIGS. 13-14. Instep 520, the method arbitrates the switch to the alternativetransceiver channel with the client module.

In an embodiment of the present invention, the various circuitcomponents are implemented using 0.35 micron or smaller CMOS technology.Provided however that other circuit technologies, both integrated ornon-integrated, may be used within the broad scope of the presentinvention.

As one of ordinary skill in the art will appreciate, the term“substantially” or “approximately”, as may be used herein, provides anindustry-accepted tolerance to its corresponding term and/or relativitybetween items. Such an industry-accepted tolerance ranges from less thanone percent to twenty percent and corresponds to, but is not limited to,component values, integrated circuit process variations, temperaturevariations, rise and fall times, and/or thermal noise. Such relativitybetween items ranges from a difference of a few percent to order ofmagnitude differences. As one of ordinary skill in the art will furtherappreciate, the term “coupled”, as may be used herein, includes directcoupling and indirect coupling via another component, element, circuit,or module where, for indirect coupling, the intervening component,element, circuit, or module does not modify the information of a signalbut may adjust its current level, voltage level, and/or power level. Asone of ordinary skill in the art will also appreciate, inferred coupling(i.e., where one element is coupled to another element by inference)includes direct and indirect coupling between two elements in the samemanner as “operably coupled”. As one of ordinary skill in the art willfurther appreciate, the term “compares favorably”, as may be usedherein, indicates that a comparison between two or more elements, items,signals, etc., provides a desired relationship. For example, when thedesired relationship is that signal 1 has a greater magnitude thansignal 2, a favorable comparison may be achieved when the magnitude ofsignal 1 is greater than that of signal 2 or when the magnitude ofsignal 2 is less than that of signal 1.

As the term module is used in the description of the various embodimentsof the present invention, a module includes a functional block that isimplemented in hardware, software, and/or firmware that performs one ormore module functions such as the processing of an input signal toproduce an output signal. As used herein, a module may containsubmodules that themselves are modules. When implemented in software orfirmware, each module can be implemented using a single processingdevice or a plurality of processing devices. Such a processing devicemay be a microprocessor, micro-controller, digital signal processor,microcomputer, central processing unit, field programmable gate array,programmable logic device, state machine, logic circuitry, analogcircuitry, digital circuitry, and/or any device that manipulates signals(analog and/or digital) based on operational instructions that arestored in a memory. The memory may be a single memory device or aplurality of memory devices. Such a memory device may be a read-onlymemory, random access memory, volatile memory, non-volatile memory,static memory, dynamic memory, flash memory, cache memory, and/or anydevice that stores digital information. Note that when the processingmodule implements one or more of its functions via a state machine,analog circuitry, digital circuitry, and/or logic circuitry, the memorystoring the corresponding operational instructions may be embeddedwithin, or external to, the circuitry comprising the state machine,analog circuitry, digital circuitry, and/or logic circuitry.

Thus, there has been described herein an apparatus and method, as wellas several embodiments including a preferred embodiment, forimplementing a multimedia client/server system, multimedia servermodule, client module and radio receiver. Various embodiments of thepresent invention herein-described have features that distinguish thepresent invention from the prior art.

It will be apparent to those skilled in the art that the disclosedinvention may be modified in numerous ways and may assume manyembodiments other than the preferred forms specifically set out anddescribed above. Accordingly, it is intended by the appended claims tocover all modifications of the invention which fall within the truespirit and scope of the invention.

1. A multimedia server comprising: an encoder for generating an encodedsignal from a multimedia input signal; a first transceiver thatmodulates an encoded signal to produce a first radio frequency (RF)signal and that transmits the first RF signal, that includes apacketized video signal, to a client over a first transceiver channelwhen the first transceiver is in a transceive mode, the firsttransceiver including: a first channel controller that performs a firstchannel scan during a quiet time between video packet acknowledgementswhen the first transceiver is in a scan mode, that determines at leastone performance parameter of the first transceiver channel and asserts alow performance signal when the at least one performance parametercompares unfavorably to a performance threshold, and that switches thefirst transceiver to a selected alternative transceiver channel when thelow performance signal is asserted; a second transceiver for modulatingthe encoded signal to produce a second RF signal and for transmittingthe second RF signal over a second transceiver channel when the secondtransceiver is in a transceive mode, wherein the second transceiverincludes: a second channel controller that performs a second channelscan when the second transceiver is in a scan mode and wherein theswitch is coupled to the second channel controller, and wherein thesecond channel scan includes determining at least one performanceparameter of a plurality of alternative transceiver channels andselecting the selected alternative transceiver channel of the pluralityof alternative transceiver channels; wherein the first transceiverchannel is a channel of a broadband wireless access network thatconforms to at least one of the following standards: 802.11x, UltraWideband (UWB), and Worldwide Interoperability for Microwave Access(WiMAX).
 2. The multimedia server of claim 1 wherein the first channelscan includes determining at least one performance parameter of aplurality of alternative transceiver channels and selecting the selectedalternative transceiver channel of the plurality of alternativetransceiver channels.
 3. The multimedia server of claim 1 wherein thefirst channel controller performs the first channel scan in response tothe low performance signal.
 4. The multimedia server of claim 1 whereinthe first channel controller performs the first channel scan in responseto the expiration of a time interval.
 5. The multimedia server of claim1 wherein the first transceiver is coupled to a first antenna and thesecond transceiver is coupled to a second antenna that is spatiallydiverse from the first antenna.
 6. The multimedia server of claim 1wherein the first transceiver further transmits switch data to theclient.
 7. The multimedia server of claim 1 wherein the first channelcontroller further arbitrates the switch to the alternative transceiverchannel with the client.
 8. A multimedia server comprising: a firsttransceiver that modulates an encoded signal to produce a first radiofrequency (RF) signal and that transmits the first RF signal to a clientover a first transceiver channel when the first transceiver is in atransceive mode, the first transceiver including: a first channelcontroller that determines at least one performance parameter of thefirst transceiver channel and asserts a low performance signal when theat least one performance parameter compares unfavorably to a performancethreshold, and that switches the first transceiver to a selectedalternative transceiver channel when the low performance signal isasserted; a second transceiver for modulating the encoded signal toproduce a second RF signal and for transmitting the second RF signalover a second transceiver channel when the second transceiver is in atransceive mode, the second transceiver including: a second channelcontroller that performs a second channel scan when the secondtransceiver is in a scan mode, wherein the second channel scan includesdetermining at least one performance parameter of a plurality ofalternative transceiver channels and selecting the selected alternativetransceiver channel of the plurality of alternative transceiverchannels.
 9. The multimedia server of claim 8 wherein the first channelscan includes determining at least one performance parameter of aplurality of alternative transceiver channels and selecting the selectedalternative transceiver channel of the plurality of alternativetransceiver channels.
 10. The multimedia server of claim 8 wherein thefirst RF signal includes a packetized video signal and the secondchannel controller performs the second channel scan during a quiet timebetween video packet acknowledgements.
 11. The multimedia server ofclaim 8 wherein the first channel control performs the first channelscan in response to the low performance signal.
 12. The multimediaserver of claim 8 wherein the first channel controller performs thefirst channel scan in response to the expiration of a time interval. 13.The multimedia server of claim 8 further wherein the first transceiveris coupled to a first antenna and the second transceiver is coupled to asecond antenna that is spatially diverse from the first antenna.
 14. Themultimedia server of claim 8 wherein the first transceiver is furthertransmits switch data to the client.
 15. The multimedia server of claim8 wherein the first channel controller is further arbitrates the switchto the alternative transceiver channel with the client.
 16. Themultimedia server of claim 8 wherein the first transceiver channel is achannel of a broadband wireless access network that conforms to at leastone of the following standards: 802.11x, Ultra Wideband (UWB), andWorldwide Interoperability for Microwave Access (WiMAX).
 17. Themultimedia server of claim 8 further comprising: an encoder forgenerating an encoded signal from a multimedia input signal thatincludes a composite video signal.